JPH02173034A - Epoxy resin - Google Patents

Abstract

PURPOSE:To provide a silicone-modified epoxy resin improved in low-stress properties, toughness, etc., and desirable for semiconductor sealing by modifying an epoxy resin with a silicone in a modification ratio above a specified value. CONSTITUTION:A silicone-modified epoxy resin is produced by modifying an epoxy resin with a silicone so that the ratio of modification with silicone as determined from the equation may fall in the range: 95<=R<=100 (wherein A is a ratio of the peak area S of the silicone compound separated by thin-layer chromatography performed by using an organic solvent of a solvent strength <=0.25 and developing the sample solution by using a silica gel as an adsorbent to the peak area T of the standard substance cholesterol acetate, B is a weight ratio of the silicone-modified epoxy resin in the sample solution to the standard substance, C is the silicone component content in the silicone-modified epoxy resin, K is the weight ratio of the silicone compound corresponding to the unit area of the silicone compound peak to the cholesterol acetate corresponding to the unit area of the standard substance).

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a silicone-modified epoxy resin with a high modification rate suitable for a resin composition for semiconductor encapsulation.

(Prior art) Epoxy resin is a resin with excellent heat resistance, electrical properties, mechanical strength, and adhesive properties, and is widely used in paints, adhesives, resins for sealing electronic parts, resins for laminates, and many other fields. It is a resin that has

However, one problem that has not been solved yet is that it is hard and brittle, that is, it is not strong.

For example, epoxy resin compositions are most commonly used in large quantities for resin encapsulation of semiconductor elements and electronic circuits such as ICs, LSIs, l-lan sisters, and diodes, from the viewpoint of characteristics, cost, and the like.

However, as these semiconductor devices tend to become highly integrated and large in size, as typified by 4MDRAM, internal stress due to the difference in thermal expansion coefficient between the semiconductor device and the encapsulating resin composition increases. tc which was not seen much in chips
Cracks in the package, damage to the IC chip, and a decrease in moisture resistance due to these have become problems.

In order to improve these defects, the performance required of epoxy resins is ■lower stress (lower modulus of elasticity, lower coefficient of thermal expansion)
, ■ Toughness (high strength) is desired, and the unresolved problems mentioned above remain as drawbacks, and there is a strong desire to improve these.

As a measure to improve these problems, we added and dispersed silicone oil, silicone compounds such as silicone rubber, or thermoplastic resins such as synthetic rubber to conventional epoxy resins, and created a polymer alloy to reduce stress and strengthen the resin. is being planned.

The performance of products to which modifiers have been added using these methods has been greatly improved and the range of use has expanded, but the addition of these modifiers also improves molding processability (mold contamination, occurrence of resin flakes, and molding voids). (e.g., the occurrence of printing defects) and the occurrence of poor sealing properties are likely to become even worse.

These molding processability (mold stains, resin cracks, molding voids,
The reason why poor mold releasability and marking properties occur is that these modifier components stand out on the surface of the molded product during the molding process.
These modifier components have poor compatibility with the epoxy resin,
Moreover, this is due to the fact that it has a low surface tension.

In order to improve these problems, it has been proposed to use a silicone compound and an epoxy resin reacted in advance (for example, JP-A-62-212417, etc.).

By using these silicone-modified epoxy resins, the embossment of the silicone compound can be suppressed to some extent, resulting in improved molding processability and imprintability, as well as epoxy resins with low stress properties and improved toughness to some extent, but they are still not satisfactory. The reason for this is that silicone compounds and epoxy resins are compounds that are poorly compatible with each other, so their reactivity is poor and a silicone-modified epoxy resin with a high reaction rate cannot be obtained.

For this reason, conventionally available silicone-modified epoxy resins contained a large amount of unreacted silicone compounds, making it impossible to obtain one that satisfied moldability and stampability.
Furthermore, the effects of improving low stress properties and toughness were also insufficient.

As a result of intensive research on these points, we have found that in order to maximize the benefits of silicone-modified epoxy resin, it is necessary to use a silicone-modified epoxy resin with a high modification rate where the reaction rate between the silicone compound and the epoxy resin is above a certain value. It was discovered that by using this resin, an extremely superior epoxy resin for semiconductor encapsulation, which could not be obtained in the past, could be obtained.

(Problems to be Solved by the Invention) An object of the present invention is to provide a silicone-modified epoxy resin with a high modification rate that is suitably used in an epoxy resin composition for semiconductor encapsulation.

(Means for Solving the Problems) In order to solve these problems, the present inventors have carried out intensive research and conducted the following chromatography using an organic solvent with a solvent strength of 0.25 or less and developing silica gel as an adsorbent. The silicone modification rate determined by formula (1) is 95≦R
The present invention was completed by discovering that a silicone-modified epoxy resin having a molecular weight of 100% or less is most suitable as an epoxy resin for semiconductor encapsulation.

R= (1-KA/BC)XI 00... CI)A
: S/T (Peak area S of a silicone compound separated into Rf [0.7 to 0.9 range) by thin layer chromatography developed using an organic solvent with a solvent strength of 0.25 or less and using silica gel as an adsorbent. and Rf value 0.4~0
．． Ratio to peak area T of standard substance cholesterol acetate separated into a range of 6) B: Weight of silicone-modified epoxy resin in sample solution/
Weight of standard substance in sample solution C: Silicone component content in silicone-modified epoxy resin (wt% of silicone compound added during silicone-modified epoxy resin production reaction) K: Weight of silicone compound corresponding to unit area of silicone compound peak / Weight of cholesterol acetate per unit area of standard substance The high modification rate silicone-modified epoxy resin of the present invention is:
It is necessary that the silicone modification rate R is 95≦R≦100, and these silicone-modified epoxy resins have less unreacted silicone compounds, so when used in an epoxy resin composition for semiconductor encapsulation, These unreacted silicone compounds do not protrude onto the surface of the molded product and do not deteriorate molding processability or stamping properties, and most of the silicone compounds are incorporated into the three-dimensional crosslinked structure of the epoxy resin. The particle size of the silicone becomes extremely small, resulting in improved thermal shock resistance and soldering heat resistance.

In addition, since there is little unreacted silicone compound, the particle size of silicone can be controlled very accurately depending on the chain length and structure of the silicone compound, so it has an extremely excellent feature that material design can be done extremely easily and accurately.

The invention will be explained in detail below.

(Measurement of silicone modification rate R) Using a thin layer chromatography automatic detection device TH-10 manufactured by Diatron Co., Ltd. as thin layer chromatography, TL
Silica gel was used as C, and a nonpolar organic solvent with a solvent strength of 0.25 or less, such as benzene, toluene, hexane, etc., was used as the developing solvent. Since unreacted silicone compounds are non-polar, they are developed and separated using a non-polar solvent.

A solution of a silicone-modified epoxy resin in an organic solvent to which cholesterol acetate was added as a standard substance was added to TLC in a few microns.
g-100 μg was spotted and developed with the above developing solvent over a distance of 5 to 15 cm.

After drying and removing the developing solvent, the peak area of unreacted silicone compound and the peak area of cholesterol acetate are obtained using a thin layer chromatograph automatic detection device.

Using these area ratios, the modification rate R of the silicone-modified epoxy resin is calculated by formula (1).

In addition, if the modification rate R of a general silicone-modified epoxy resin obtained from conventional literature etc. is measured by these methods,
The modification rate R was 5 to 80%.

(Synthesis of high modification rate silicone-modified epoxy resin) The epoxy resin used as a raw material for the high modification rate silicone-modified epoxy resin of the present invention may be any resin as long as it has two or more epoxy groups in one molecule. Examples include bisphenol A epoxy resin, bisphenol F epoxy resin, phenol novolak epoxy resin, Talezol novolak epoxy resin, alicyclic epoxy resin, and modified resins thereof, and these epoxy resins may be used in combination of one or two types. It is possible to use a mixture of more than one species. Among these epoxy resins, the epoxy equivalent is 150
~250°C, a softening point of 60°C to 130°C, and preferably free of ionic impurities such as Na'' and CI- as much as possible.

Furthermore, the organosiloxane used as one of the raw materials for the high modification rate silicone-modified epoxy resin of the present invention has a functional group that can react with the above-mentioned epoxy resin, and examples of the functional group include an epoxy group, an alkoxy group, a hydroxyl group, and an amino group. group, hydroxyl group, etc., and the molecular structure may be either linear or branched.

Furthermore, the method for synthesizing the highly modified silicone-modified epoxy resin in the present invention is not particularly limited, but as an example, an organopolysiloxane having two or more amine groups may be reacted with some epoxy groups of an epoxy resin. At least a block adduct can be obtained, or a block adduct can be obtained by a hydrosilylation reaction of an alkenyl group-containing epoxy resin and an organopolysiloxane having two or more hydrosilyl groups under a chloroplatinic acid catalyst in the presence of a solvent. There is a synthesis method. In short, no matter which method is used, it is important in the present invention to minimize the amount of unreacted organopolysiloxane, and if necessary, remove these unreacted organopolysiloxanes by washing, extraction, etc. from the obtained reactant. Methods such as removing organopolysiloxane can also be used as appropriate.

(Function) These high modification rate silicone-modified epoxy resins must have a reaction rate R of 95≦R≦100, and if the modification rate R is less than 95, the unreacted organosiloxane component in the epoxy resin Since it also concentrates in the silicone domain, the diameter of the silicone domain becomes large.

In general, in a resin system that has a morphology of soft polymer islands in a sea of hard polymers, the smaller the particle size of the soft polymer islands, the lower the elastic modulus of the system and the greater the stress reduction effect. Therefore, as the silicone particle size increases, the low stress effect, which is the purpose of using the silicone-modified epoxy resin, becomes smaller and the resin also lacks toughness.

Furthermore, unreacted organosiloxane components have poor compatibility with epoxy resins, have low surface tension, and generally have low viscosity, so when a composition using a silicone-modified epoxy resin is molded at high temperature and pressure, unreacted components are removed from the surface of the molded product. The reactive organosiloxane component oozes out, causing failure modes such as oil stains on the molded product, mold stains, poor marking performance, and resin flakes.

If the reaction rate R is within the range of 95≦R≦lOO, these drawbacks will be improved and low stress properties and toughness will be significantly improved.

Furthermore, moisture resistance is also improved due to improved bonding strength at the epoxy/silicone interface.

Furthermore, by controlling the composition of the epoxy resin and the composition of the organosiloxane (particularly the molecular chain length), it is possible to control the compatibility between the epoxy and silicone, and to control the silicone particle size fairly accurately, resulting in product variations. is kept to a minimum.

(Example) Silicone-modified epoxy resin (1) Silicone represented by structural formula (1) obtained by reacting a reaction product of phenol novolak epoxy resin and O-allylphenol with a silicone compound having H-5i groups at both ends. A silicone-modified epoxy resin represented by the structural formula [2] obtained by reacting a silicone compound having -NH groups at both terminals with a phenol novolak epoxy resin.

”!/mrn-o, oos, k+++90, j
Ll.

Example 1 Silicone-modified epoxy resin (1) was synthesized in the following manner.

100 parts by weight of a phenol novolac epoxy resin (epoxy equivalent: 190, softening point 70°C) was placed in a reaction apparatus equipped with a stirrer, heat exchanger, and swell meter, heated to 100°C, and heated under a reduced pressure of 3 Q Torr while stirring. The water content in the epoxy resin was kept at 1 wt% (Karl Fischer method) or less by holding for 1 hour.

Next, the pressure was returned to normal, and at the same temperature, 3 parts by weight of monoallylphenol and 1,8-diazabicyclo(5,4,0) were added as a catalyst.
A mixture of 1 part by weight of undecene-7 (DBU) was added dropwise over a period of 10 minutes, and the mixture was further stirred at 110°C for 4 hours to obtain an allylated epoxy.

When the allylation rate of the allylated epoxy was measured using a gas chromatograph, the allylation reaction rate was approximately 100%.

Further, in a reaction vessel similar to the above, 100 parts by weight of the allylated epoxy obtained, 100 parts by weight of toluene as a solvent, 0 dimethyl silicone compounds having H-5i groups at both ends (
Average degree of polymerization: 185. 10 ethylphenyl groups in the side chain,
25 parts by weight of those having 5 γ-glycidoxyprobyl groups were mixed and subjected to azeotropic dehydration for 1 hour, followed by isopropyl alcohol solution of chloroplatinic acid (1 wt%) as a catalyst.
0.1 overlapping portions were added dropwise over a dropping time of 10 minutes, and the reaction was further carried out at reflux temperature for 6 hours.

After that, the reaction solution was heated to 110°C while the solvent was flowing out at normal pressure.
The temperature was raised to 130 Torr and maintained for 1 hour under a reduced pressure of 30 Torr to obtain a silicone-modified epoxy resin.

Evoquine equivalent of the obtained silicone-modified epoxy resin,
Modification rate R1 softening point was measured.

Further obtained silicone modified epoxy resin 100w
7 enol nopolac resin (
Softening point 110°C! , OH equivalent 105) and D as catalyst
1 part by weight of BtJ was mixed and finely pulverized to obtain a powder resin molding material, which was then formed into tablets and then subjected to transfer molding.

The length of the slint burr during molding, the elastic modulus of the molded product, and the thermal expansion coefficient of the molded product at room temperature were measured.

The results are shown in Table 1.

Example 2 Silicone-modified epoxy resin (2) was synthesized in the following manner.

In a reaction apparatus equipped with a stirrer, a heat exchanger, and a thermometer, 100 parts by weight of a phenol novolane epoxy resin (epoxy weight 2190, softening point 70°C) and a dimethyl silicone compound having primary amino groups at both ends (average polymerization 200° C.) and 100 parts by weight of butanol were added, heated to 110° C. to dissolve, and stirred for 4 hours to react.

Thereafter, the mixture was maintained under a reduced pressure of 3 Q Torr for 1 hour to completely remove butanol to obtain a non-recone modified epoxy resin.

The obtained silicone-modified epoxy resin was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 1 The same operation as in Example 1 was carried out except that the dehydration operation in step ① reaction was omitted, and an epoxy resin without pre-drying (
A silicone-modified epoxy resin was obtained using the Karl Fischer method with a water content of 0°4%.

When the amount of unreacted 0-allylphenol in the allylated epoxy resin obtained in the first stage reaction was determined by gas chromatography, it was found that 30 to 35% of the input amount was unreacted. The reason for this is thought to be that DBU used as a catalyst was hydrolyzed and the catalytic activity decreased. Since these free 0-allylphenols easily reacted with the dimethyl silicone compound having H-3i groups at both ends, the free corn modification rate R decreased.

The properties of the obtained resin were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 2 A silicone-modified epoxy resin was obtained by carrying out the same reaction as in Example 2 except that the solvent in the reaction conditions was changed to methyl isobutyl ketone.

The solubility of silicone compounds and epoxy resins is lower in methyl isobutyl ketone than in butanol, so they cannot be mixed well and the reaction is not sufficient, so the free corn modification rate R
decreased.

The properties of the obtained resin were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 3 In the reaction of Example 2, an epoxy resin and a silicone compound were reacted in a molten mixed state without using butanol as a solvent to obtain a silicone-modified epoxy resin.

In a solvent-free reaction, the silicone compound cannot be uniformly dispersed in the epoxy resin, resulting in a non-uniformly dispersed state with particle diameters of several tens to several hundreds of micrometers, so that the reaction is insufficient and the silicone modification rate R decreases.

The properties of the obtained resin were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 4 A powdered resin was obtained in exactly the same manner as in Example 1 using a phenol novolak epoxy resin (epoxy weight: 90, softening point: 70'C) that was not modified with silicone, and the same evaluation was performed. Shown in the table.

(Margin below) Book 1 *2 R= (1-KA/BC)X I OO・ ・ ・ C
I) A: S/T (Peak area S and Rf of silicone compounds separated into Rf values in the range of 0.7 to 0.9 by thin layer chromatography developed using benzene as a developing solvent and silica gel as an adsorbent) Ratio to the peak area T of the standard substance cholesterol acetate separated into a value range of 0.4 to 0.6) B: Weight 1/of silicone-modified epoxy resin in the sample solution
Weight of standard substance in sample solution C: Silicone component content in silicone-modified epoxy resin (wt% of silicone compound added during silicone-modified epoxy resin production reaction) K: Weight of silicone compound corresponding to unit area of silicone compound peak / Cholesterol acetate weight per unit area of standard substance Width 10 μl from the vent part I; Length of resin Paris.

Molding conditions: mold temperature 175°C.

The injection pressure is 80 kgf/cm.

Test piece measured as follows: Dimension 1 oxa OX5 (+n+u) hardening 1
Cured at 75°C for 5 minutes, then cured at 175°C for 16 hours. Measurement: Tensilon bending strength measuring machine, span 40mm, crosshead descending speed 20 mn+/n+in. Test piece: Dimensions: 5 x 5 x 15 (mm), cured at 175°.
Curing after C5 minutes at 175°C 16 hours measurement: TMA (Thermal Expansion Analyzer I) Temperature increase rate lO°C/ll1in

Claims (1)

[Claims] (1) Silicone modification rate R determined from the following formula [I]
is 95≦R≦100. Silicone-modified epoxy resin R = (1-KA/BC) The peak area S of silicone compounds separated into Rf values in the range of 0.7 to 0.9 and the standard substance cholesterol acetate separated into Rf values in the range of 0.4 to 0.6 by thin layer chromatography developed using (ratio to peak area T) B: Weight of silicone-modified epoxy resin in sample solution/
Weight of standard substance in sample solution C: Silicone component content in silicone-modified epoxy resin (wt% of silicone compound added during silicone-modified epoxy resin production reaction) K: Weight of silicone compound corresponding to unit area of silicone compound peak /Cholesterol acetate weight per unit area of standard material